Don't be scared off by weird terminology. Half the point of problems like this is to convince people that they can't solve it because they've never studied pars before. But when they use these obscure math terms, they will always define it for you. Just follow directions!
Anyway a par apparently is just half the area of the rectangle. So let's figure out the area of the rectangle and try not to forget to divide it in half at the end. It helps to draw a picture. If the width is 2, then the width of the opposite side is obviously 2 as well. Since the perimeter is 24, we have 20 left, to divide between the other two sides. So the other 2 sides must be 10 each.
Thus, the area of this rectangle is 20. If you forget to divide by 2 you'll get the wrong answer, but since the par is 10, the answer is B.
_________________





Need help with GRE math? Check out our groundbreaking books and app.